Commit 0076a275 authored by serrano's avatar serrano

Added some considerations on I/O FFs

git-svn-id: http://svn.ohwr.org/vme64x-core/trunk@178 665b4545-5c6b-4c24-801b-41150b02b44b
parent 1ce0c1bf
......@@ -16,7 +16,13 @@ especially considering that one of them will not use the I/O FFs. If
these double-clocked signals are really needed, the triple-clocking
block could deliver an extra ouput port for them.
There are a number of outputs which are supposed to go to the outside
world (VME_DTACK_n_o, WE_o, VME_DATA_DIR_o...) and which are not using
I/O FFs because they are the result of some combinational logic. This
will result in tricky timing issues, and need complex constraints to
P&R to guarantee consistent results. I would strongly advice to make
sure all these signals are outputs of I/O FFs, with any necessary
logic placed *before* these FFs.
TODO:
- Check iack_in -> iack_out part.
......
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